Apparatus For Testing Loss-Of-Coolant Accident Using Model Of Nuclear Containment Building

ABSTRACT

Provided is an apparatus for testing a loss-of-coolant accident using a model of a nuclear containment building, including a containment vessel of which an upper surface is opened and side and lower surfaces are transparent; an internal structure which is disposed in the containment vessel; a hose pipe which is disposed at an upper side of the containment vessel; and a measuring device which is disposed at the lower surface of the containment vessel so as to monitor movement of fluid and debris in the containment vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority of Korean Patent Application No.10-2012-0022989, filed on Mar. 6, 2012, which is incorporated herein byreference.

FIELD

The present invention relates to an apparatus for testing aloss-of-coolant accident using a model of a nuclear containmentbuilding.

BACKGROUND

Generally, safety equipment for nuclear power plants is designed inconsideration of a design basis accident such as a loss-of-coolantaccident. In case that a control rod is not operated or the accidentcannot be solved with only the control rod, an ECCS (Emergency CoreCooling System) in a nuclear reactor is operated. Herein, water storedin a RWST (Refueling Water Storing Tank) is used as a source of watersupply of a spray pump so as to cool the nuclear reactor. If the waterin the RWST is exhausted, it is converted into a recirculation operatingmode using a recirculation sump so as to continuously circulate thecoolant. To this end, the ECCS includes a recirculation pump, astrainer, a recirculation sump and the like.

However, even though the ECCS is operated, a main pipe may be brokenupon the loss-of-coolant accident (LOCA), and thus debris including amaterial forming the pipe, a heat insulation material and othermaterials may be generated due to non-chemical and chemical reactions ina containment vessel. The debris may obstruct a fluid passage for therecirculation cooling and thus the cooling process may not performsmoothly. That is, the debris may be transported to the bottom of anuclear reactor building, and the recirculation may be prevented orclogging may occur at a filtering screen. Further, if the debris isexcessively accumulated at a certain place, the pump may be damaged.

FIG. 1 shows the LOCA situation. Herein, the pipe in the primarycontainment vessel is damaged, the coolant is flowed to the bottom ofthe containment vessel, the RWST is operated, and the coolant passingthrough the strainer and collected in the water container is used again.If the clogging has occurred at the strainer due to the debris, the pumpis overloaded and the recirculation cooling may not perform smoothly.

Distribution and transport ratio of the debris may be changed accordingto the damaged position and an influence of the debris may be alsochanged. It is necessary to analyze an influence exerted on head loss inconsideration of various factors such as transport of the debris,chemical interaction in the flowing at a front side of the strainer,generation and decomposition of chemical particles in recirculatedwater, and head loss. However, information about the distribution,transport speed and transport rate of the debris is not actuallyprovided.

In Korean Patent Application No.10-2008-0064121, there is disclosed amonitoring method for calculating an unidentified leak rate of a reactorcoolant system by using a kalman filter or kalman smoother. However, inthe monitoring method, the leak rate is just provided as a numericalvalue, and the actual information about the distribution, transportspeed and transport rate of the debris generated by a pipe breakingaccident is not provided.

SUMMARY

An embodiment of the present invention is directed to providing anapparatus for testing a loss-of-coolant accident using a model of anuclear containment building, which can visually provide informationabout a flow rate upon LOCA, distribution of debris and the like.

To achieve the object of the present invention, the present inventionprovides an apparatus for testing a loss-of-coolant accident using amodel of a nuclear containment building, including a containment vesselof which an upper surface is opened and side and lower surfaces aretransparent; an internal structure which is disposed in the containmentvessel; a hose pipe which is disposed at an upper side of thecontainment vessel; and a measuring device which is disposed at thelower surface of the containment vessel so as to monitor movement offluid and debris in the containment vessel.

In an embodiment, preferably, a water container part is disposed at thelower surface of the containment vessel and connected with the hosepipe.

In an embodiment, preferably, the hose pipe is movable in alldirections.

In an embodiment, preferably, the hose pipe further includes a heaterfor heating injected fluid, and a debris storing part for injectingnon-chemical and chemical debris generated upon an actual accident.

DRAWINGS

FIG. 1 is a view showing a state of a loss-of-coolant accident (LOCA).

FIGS. 2 and 3 are views showing a test apparatus according to thepresent invention.

Detailed Description of Main Elements 11: hose pipe 12: containmentvessel 13: internal structure 14: side surface 15: water container part16: measuring device 17: lower surface

DETAILED DESCRIPTION

Hereinafter, the embodiments of the present invention will be describedin detail with reference to accompanying drawings.

FIG. 2 shows a model of a containment vessel according to the presentinvention. A containment vessel 12 which miniaturizes a containmentvessel of an actual nuclear reactor is provided as the model of thecontainment vessel. An internal structure 13 which miniaturizes aninternal structure of the actual nuclear reactor is disposed in thecontainment vessel 12. The containment vessel 12 and the internalstructure 13 may be changed according to the nuclear reactor.

A hose pipe 11 is formed at an upper side of the containment vessel 12so as to be moved in all directions. Because the configuration formoving the hose pipe 11 can be embodied with well-known technology, thedescription thereof will be omitted. The hose pipe 11 is to showdischarge of the coolant from a broken portion when a loss-of-coolantaccident (LOCA) occurs.

One end of the hose pipe 11 is directed to an inner side of thecontainment vessel and the other end is connected with a water supplydevice (not shown) and a water container. The hose pipe 11 is moved to aplace in the containment vessel, in which the broken accident isoccurred.

An upper end of the containment vessel is opened so as to supply waterthrough the horse pipe 11, and side and lower surfaces thereof areformed of a transparent material so as to facilely observe an inner sidethereof. The containment vessel may be formed by miniaturizing acontainment vessel of an actual nuclear reactor at a desired rate, and acore and the other internal structure 13 in the containment vessel maybe also formed by miniaturizing them of the actual nuclear reactor.

Particularly, since the lower surface 17 of the containment vessel isformed of a transparent material so as to observe the inner sidethereof, it is facile to observe the movement of the debris upon theLOCA and also to measure a flow rate thereof. The side surface 14 of thecontainment vessel is also formed of a transparent so as to observe theinner side thereof.

A water container part 15 is formed at a lower side of the lower surface17 of the containment vessel. A moving means such as wheels (not shown)is provided on a lower surface of the water container part 15 so thatthe water container part 15 can be located at a place corresponding tothe water container formed in the actual containment vessel, therebyreflecting a design of the actual nuclear reactor.

For convenience of explanation, an end of the water container part 15 isshown to be spaced apart from the containment vessel 12, but the watercontainer part 15 is closely contacted with a lower portion of thecontainment vessel so that the coolant passing the lower side of thecontainment vessel is discharged through the water container part.

Further, one end of the water container part may be connected with anend of the horse pipe 11. That is, the coolant passing the bottom of thecontainment vessel passes the water container and then discharged againto the hose pipe 11. In other words, when the broken accident isoccurred, it is possible to observe movement of the debris during therecirculation process of the coolant and thus to analyze the problemswhich are occurred at the recirculation process of the coolant.

A measuring device is provided at a lower side of the testing apparatus.The measuring device functions to observe the movement of the debris inthe containment vessel. Further, the measuring device is movablydisposed in order to observe the inner side of the containmenteverywhere. That is, the measuring device measures a moving speed of thedebris at a certain place.

In the prior art, hydrodynamic analysis was needed to estimate aninfluence of a structure. In this case, only a value was calculated at acertain place. When manufacturing the testing apparatus, a ball or otherfloating matter was used to measure a speed of fluid by making a videothereof. However, in the present invention using a laser beam, when thedebris are passed, an interference phenomenon is occurred at a surfaceof a detector due to dispersion of light, and the speed of fluid can bedirectly measured by obtaining a frequency with respect to the speedusing Doppler Effect.

Further, according to the present invention, when a position of the pipeis changed, it is possible to intuitively recognize the movement andpassage of the debris by generally allowing the visualization of them.

Particularly, since it is possible to change positions of the hose pipeand the water container part and also to change a position of theinternal structure in the containment vessel, the present invention canbe applied to any type of containment vessels.

FIG. 3 shows the testing apparatus when viewing from a lower sidethereof. Since the measuring device is disposed at the lower side of thetesting apparatus, it is possible to measure a flow rate and anaccumulated degree of the debris at a desired place. Therefore, thecontainment vessel 12 is disposed to be spaced apart from the ground ina desired distance. The water container part is also movable by themoving means.

Further, the present invention may additionally include a circulationheating heater for heating the fluid, a flow meter for measuring a flowrate of the fluid, a sensor for sensing a change in temperature andpressure of the fluid.

Further, in order to embody an actual accident, the fluid injectedthough the hose pipe has temperature and pressure which are the same asthe temperature and pressure upon an actual accident, and also thechemical and non-chemical debris which are the same as them upon theactual accident can be injected into the fluid. To this end, the hosepipe may further include a debris injecting device.

Further, in order to embody the case that the head loss is generated,the flow rate of the fluid may be changed.

FIG. 4 shows the testing apparatus including a separate measuring deviceand a displaying device. According to the testing apparatus of thepresent invention, since the upper side of the testing apparatus isopened and the side and lower surfaces thereof are formed of thetransparent material, it is possible to simultaneously perform themeasurement in all directions or in only one direction.

The measuring device may further include a transmittance measuringdevice for measuring a transmittance of light. When light is radiatedfrom one of the upper and lower side of the containment vessel or fromboth of them, the transmittance measuring device calculates atransmitted and reflected light amount and thus calculates a degree ofthe debris accumulated in the containment vessel. The transmittancemeasuring device may be disposed independently. Therefore, in thepresent invention, it is possible to actually measure the accumulateddegree of the debris. In addition, in order to compensate lightrefraction according to materials of the fluid and the containmentvessel, a refraction compensating part having separate fluid forcompensating the light refraction is further included at the upper orlower surface thereof so as to compensate an error of the transmittanceaccording to the light refraction.

According to the test apparatus of the present invention, it is possibleto provide the visible data about the LOCA in the nuclear reactor.

While the present invention has been described with respect to thespecific embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

What is claimed is:
 1. An apparatus for testing a loss-of-coolantaccident using a model of a nuclear containment building, comprising: acontainment vessel of which an upper surface is opened and side andlower surfaces are transparent; an internal structure which is disposedin the containment vessel; a hose pipe which is disposed at an upperside of the containment vessel; and a measuring device which is disposedat the lower surface of the containment vessel so as to monitor movementof fluid and debris in the containment vessel.
 2. The apparatus of claim1, wherein a water container part is disposed at the lower surface ofthe containment vessel and connected with the hose pipe.
 3. Theapparatus of claim 2, wherein the hose pipe is movable in alldirections.
 4. The apparatus of claim 3, wherein the hose pipe furthercomprises a heater for heating injected fluid, and a debris storing partfor injecting non-chemical and chemical debris generated upon an actualaccident.
 5. The apparatus of claim 1, further comprising atransmittance measuring device which calculates a transmittance of lightand thus calculates an accumulated degree of the debris.